1. Field of the Invention
This invention relates to an electric shutter control means, and more particularly to a device for controlling the shutter speed of a focal plane type electric shutter in which the exposure time determined by an electric circuit is modified by a mechanical delay means.
2. Description of the Prior Art
In general, the leading curtain and the trailing curtain of a focal plane shutter are overlapped when the shutter is closed to prevent leakage of light therethrough. Therefore, the distance from the starting position of the leading curtain to the position where the leading curtain begins to expose the film to light incident into the camera is not equal to the distance from the starting position of the trailing curtain to the position where the trailing curtain begins to cover the film. Because of this difference, it is very difficult to practice to make the time between the start of the leading curtain and the trailing curtain, i.e. the delay of the start of the trailing curtain with respect to the start of the leading curtain, equal to the exposure time. In the manufacture of this type of electric focal plane shutter, therefore, there are great design and production difficulties in adjusting the starting position of the leading curtain, determining the proper amount of overlapping of the shutter curtains, adjusting the operation time of various mechanical levers and other members to move the shutter curtains and so forth.